[PATCH] D123576: Support constructing empty function_ref from other callables that can be "empty"

[David Blaikie via Phabricator via llvm-commits]

dblaikie added a subscriber: rsmith.
dblaikie added a comment.

I worry this is overly general (it's not obvious that any functor with boolean conversion has the semantics this patch relies on) & inconsistent with the standard library (`std::function` for instance doesn't provide this (or a narrower version of it) functionality - so we'll still have the bugs for any API that takes a `function_ref` and passes it to `std::function`)

I don't know that there's /no/ useful direction here, but I have my reservations.

(@rsmith as the original author of `function_ref`)


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D123576/new/

https://reviews.llvm.org/D123576